Effects of Testosterone Supplementation for 3 Years on Muscle Performance and Physical Function in Older Men

Abstract

Context: Findings of studies of testosterone's effects on muscle strength and physical function in older men have been inconsistent; its effects on muscle power and fatigability have not been studied.

Objective: To determine the effects of testosterone administration for 3 years in older men on muscle strength, power, fatigability, and physical function.

Design, setting, and participants: This was a double-blind, placebo-controlled, randomized trial of healthy men ≥60 years old with total testosterone levels of 100 to 400 ng/dL or free testosterone levels <50 pg/mL.

Interventions: Random assignment to 7.5 g of 1% testosterone or placebo gel daily for 3 years.

Outcome measures: Loaded and unloaded stair-climbing power, muscle strength, power, and fatigability in leg press and chest press exercises, and lean mass at baseline, 6, 18, and 36 months.

Results: The groups were similar at baseline. Testosterone administration for 3 years was associated with significantly greater performance in unloaded and loaded stair-climbing power than placebo (mean estimated between-group difference, 10.7 W [95% confidence interval (CI), -4.0 to 25.5], P = 0.026; and 22.4 W [95% CI, 4.6 to 40.3], P = 0.027), respectively. Changes in chest-press strength (estimated mean difference, 16.3 N; 95% CI, 5.5 to 27.1; P < 0.001) and power (mean difference 22.5 W; 95% CI, 7.5 to 37.5; P < 0.001), and leg-press power were significantly greater in men randomized to testosterone than in those randomized to placebo. Lean body mass significantly increased more in the testosterone group.

Conclusion: Compared with placebo, testosterone replacement in older men for 3 years was associated with modest but significantly greater improvements in stair-climbing power, muscle mass, and power. Clinical meaningfulness of these treatment effects and their impact on disability in older adults with functional limitations remains to be studied.

Trial registration: ClinicalTrials.gov NCT00287586.

Figure 1.

(A) Changes in strength in the chest press exercise. (B) Changes in strength in the leg press exercise. Results represent change in mean maximal voluntary strength from baseline for each visit for men randomly assigned to testosterone (solid line) or placebo arms (dashed line) and the number of subjects completing each visit. Error bars are 95% CIs. P values are provided from linear mixed-model regression controlling for baseline values and age category.

Figure 2.

(A) Changes for peak power in the chest-press exercise. (B) Changes for peak power in the leg-press exercise. Data indicate changes from baseline in mean peak power for testosterone (solid lines) and placebo (dashed lines) groups for each visit and the number of participants completing each visit (N). Error bars are 95% CIs. P values are provided from linear mixed-model regression controlling for baseline values and age category.

Figure 3.

Mean changes from baseline at each visit for (A) unloaded and (B) loaded stair climb power. Solid lines represent data for the testosterone group; dashed lines indicate changes in the placebo group. The number of subjects completing each visit (N) is indicated. Error bars are 95% confidence intervals. P values are provided from linear mixed model regression controlling for baseline values and age category.

Figure 4.

Mean changes in lean body mass from baseline at each visit and the number of subjects at each visit (N). Solid lines represent changes for the testosterone group, and dashed lines indicate changes in the placebo group. Error bars are 95% confidence intervals. P values are provided from linear mixed model regression controlling for baseline values and age category.